Pleurobranchaea tarda has an oval sandy-coloured body with a spade-shaped head and two widely separated rolled rhinophores. It has a single gill on the right hand side of its body and can grow to be 70 mm long. It may be confused with Pleurobranchaea bubala, which is bigger and has a rougher surface, but tends to live in shallower water.
Ecology
It is an enthusiastic predator on other opisthobranchs; and has even been seen eating smaller individuals of the same species. Its egg ribbon forms a sizeable roll of several white loops.